The essentials
- The core: Shopping and Performance Max account for 60 to 80% of an online store's Google Ads sales; their quality depends on the Merchant Center feed.
- Measurement: events
purchasewith value and identifiers, enhanced conversions, Consent Mode v2; without them, no optimisation is possible. - The steering layer: target ROAS calculated from the margin, campaigns separated by margin level or priority, share of new customers tracked.
- 2026 benchmarks: ROAS of 3 to 6 depending on margins, cost per sale of 5 to 15% of the basket, minimum budget of €1,500 a month to learn.
For an online store, Google Ads is often the first paid channel: buyers search for products by name, and Google shows product listings with price and image above the classic results. Profitability depends on three things: the quality of the product feed, the reliability of sales measurement, and steering on ROAS and margin rather than on clicks. This article gives the campaign structure, the prerequisites, the steering method and 2026 benchmarks. The Google Ads basics are in Google Ads: definition and guide.
The campaigns in an e-commerce account
| Campaign | Role | Typical share of sales | Key points |
|---|---|---|---|
| Performance Max with a feed | Serves the products on Shopping, Search, Display, YouTube, Gmail and Discover, optimising on a target ROAS | 40 to 60% | Listing groups by margin or priority, audience signals, brand queries excluded if measured separately |
| Standard Shopping | Fine control of bids by product, testing | 10 to 30% | Useful for high-margin products or launches; losing ground to PMax |
| Search (keywords) | Generic and brand queries, categories, products with no feed | 10 to 25% | Dedicated category pages, price and promotion extensions |
| Remarketing and dynamic retargeting | Abandoned baskets, viewed products, cross-selling | 10 to 20% | Short segments, buyers excluded; see dynamic retargeting |
| Demand Gen, YouTube | Awareness and discovery for new products | Low directly | To be measured on the share of new customers |
The prerequisites: feed and measurement
- Merchant Center: a complete feed (id, title with brand and attributes, description, price, availability, GTIN, images, Google category, shipping costs, delivery times), updated daily, with no disapproved products; product reviews and promotions add elements to the ads.
- Optimised titles: the feed title acts as the keyword for Shopping; “Brand + type + key attributes (size, colour, material)” within the first 70 characters.
- Measuring sales: event
purchasewith value, currency, transaction ID and items, via GA4 e-commerce and GTM; enhanced conversions (hashed e-mail) to recover the sales lost to cookies; Consent Mode v2; see GA4 e-commerce. - Deduplication: a single primary conversion source (GA4 import or the Google Ads tag), the others in observation.
- Margin by product or category: known and passed through (custom labels in the feed) so you can steer on profit.
Steering on ROAS and margin
The aim of ROAS (revenue generated / advertising spend) is the steering metric, but it only means something alongside the margin: a ROAS of 4 is excellent with a 50% gross margin, insufficient with 15%. Method:
- Calculate the break-even ROAS: 1 / (gross margin in %); with a 30% margin, you need a ROAS above 3.3 to cover the advertising cost out of the margin.
- Set a target ROAS by product group according to the margin and the strategy (accepting a lower ROAS to acquire new customers with a high lifetime value).
- Separate the campaigns by margin level or priority (custom labels), to give each group its own target ROAS and budget.
- Track the share of new customers (the new customer acquisition goal in PMax, or GA4 segments): a high ROAS obtained only on existing customers does not grow the store.
- Include returns and cancellations in the value (importing adjusted conversions) so you do not optimise on fictitious sales.
2026 benchmarks
| Metric | Order of magnitude | Note |
|---|---|---|
| Overall Google Ads ROAS | 3 to 6 | Depending on margins and competition; higher on brand, lower on prospecting |
| Cost per sale | 5 to 15% of the average basket | Beyond 20%, review the feed, the targeting and the pages |
| Shopping conversion rate | 1 to 3% | Depends heavily on price and shipping costs |
| Shopping CPC, France | €0.20 to €0.80 | Higher in fashion, electronics and home |
| Minimum budget to learn | €1,500 to €3,000 per month | Below that, PMax does not get enough conversions (aim for 30 a month per campaign) |
| Share of sales from remarketing | 10 to 20% | Beyond that, the account stops winning new customers |
Seasonality and promotions
Online stores live on peaks (sales periods, Black Friday, holidays, the product's season). Anticipate them: raise the budgets 2 to 3 weeks ahead so that automated bidding can learn, use seasonality adjustments for short peaks, load the promotions into Merchant Center to show the badges, prepare dedicated creatives, check stock and delivery times in the feed. After the peak, reduce gradually rather than cutting. The classic mistakes are in the ten Google Ads mistakes.
Measuring and arbitrating with the other channels
Google Ads is only one channel: read its sales alongside those from SEO, social media, e-mail and Meta Ads in a shared dashboard, with data-driven attribution, so you know where to put the next euro. Last-click Google Ads ROAS often overstates the channel when Meta and e-mail prepare the purchase. The comparison with social ads is covered in SMA vs SEA, and overall steering in e-commerce KPIs.
How GreenRed helps
Rather than juggling several tools, GreenRed's return on investment module brings these metrics together in a single dashboard, compares them over time and tells you which actions come first. You can try it free, with no card, from the Pricing.
Frequently asked questions
What ROAS should an online store aim for on Google Ads?
The minimum ROAS is 1 divided by the gross margin: 3.3 with a 30% margin, 2 with 50%. In 2026, e-commerce accounts show overall ROAS of 3 to 6 depending on margins and competition. Set a target ROAS by product group, accepting a lower ROAS to acquire new customers with a high lifetime value.
Performance Max or standard Shopping?
Performance Max with a feed has become the main campaign: it serves on every network and optimises on ROAS. Standard Shopping keeps its value for controlling bids on high-margin products, testing or launching. Many accounts combine the two, with separate product groups to avoid competing internally.
What is the minimum budget for Google Ads in e-commerce?
Allow €1,500 to €3,000 a month for a Performance Max campaign to reach the 30 monthly conversions it needs in order to learn. Below that, favour standard Shopping on the best sellers plus remarketing, with manual steering.
How do you account for returns in ROAS?
Import the conversion adjustments (cancellations, returns) into Google Ads, or use a conversion value net of estimated returns. Without that, bidding optimises on fictitious sales and the ROAS shown overstates profitability, especially in fashion where returns exceed 20%.